Design for a battery charger



FIG. 1 is a top plan view of a battery charger embodying our new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a left side elevational view thereof;

FIG. 7 is a right perspective view thereof on a reduced scale;

FIG. 8 a top plan view of a battery charger showing a second embodiment of our new design; and,

FIG. 9 is a right perspective view thereof. 

The ornamental design for a battery charger, as shown and described. 